DAB (Digital Audio Broadcasting) is a digital transmission standard in particular for radio programs. The term DAB is used below as an umbrella term for DAB, DAB+ and DMB (Digital Media Broadcasting).
Current DAB, FM and AM radio receivers have tuner modules (receiver modules) in which the HF signals (high-frequency signals) coming from the antenna are filtered, amplified and mixed to obtain a suitable intermediate frequency. In some receiver systems, the signals are then digitized using A/D converters (analog-digital converters) and are digitally demodulated. Separate tuner modules for DAB and FM/AM are used for this purpose.
One disadvantage of this is that the bandwidth of the signal is greatly reduced for both FM/AM and DAB before digitizing the bandwidth of the signal, so that for receiving two or more signals, each of which may correspond to one transmitter, a complete receiver path including a tuner module and an A/D converter is necessary for each signal to be received.
In high-end mobile receiver systems, two or more receiver paths for FM/AM are often needed to implement functions such as improving reception through diversity algorithms, background receivers for RDS (Radio Data System) reception, monitoring TMC (Traffic Message Channel) transmitters, etc. In addition, one or more receiver paths are needed for DAB to implement, for example, DAB reception improvement (e.g., diversity) and background tuners for a transmitter list, for example.
In recent system proposals, it is provided that the entire AM band or the entire FM band is digitized with the aid of a broadband A/D converter to have the entire band in digital form. Any number of channels may then be demodulated in a digital signal processing unit, as a function of the available computation power.